Design of an IF section for a Galactic Emission Mapping experiment

In the context of the Galactic Emission Mapping collaboration, a galactic survey at 5GHz is in preparation to properly characterize the galactic foreground to the Cosmic Microwave Background Radiation (CMBR). For the North sky survey, a new receiver is being developed. This 5GHz heterodyne polarimeter has a high gain IF (intermediate frequency) chain using the latest RF technology and microstrip design that we describe in the present article. Working at 600MHz central frequency, it consists of a pre-amplifier with an integral band-pass filter followed by an amplifier with digitally controlled gain and a frequency converter to zero-IF that feeds the ADC of a four channel digital correlator (outside the scope of the present article). This paper focuses the design options and constraints and presents the simulations and experimental results of a circuit prototype.